NEW ORGANIC ALKALINE METAL SALT AND ITS USE IN BATTERY ELECTROLYTES

Abstract

The invention relates to an organic alkali metal salt of general formula (I), in which M represents an alkali metal selected from lithium and sodium. This organic salt can in particular be used in an electrolyte for lithium or sodium batteries. [Chem. 1] (I).

Description

Title of the invention: NEW ORGANIC ALKALINE METAL SALT AND ITS USE IN BATTERY ELECTROLYTES technical field

[0001] The present invention falls within the field of battery manufacturing, and more particularly lithium or sodium batteries.

[0002] More particularly, the present invention relates to a lithium- or sodium-based organic salt, free of fluorine, particularly suitable for use in batteries, as well as a method for preparing such an organic salt. The invention also relates to a liquid or solid electrolyte composition comprising such an organic salt, an electrochemical cell comprising such an electrolyte composition, and a battery comprising such an electrochemical cell. Prior art

[0003] Lithium batteries, such as lithium-ion batteries, are increasingly used as a stand-alone power source, particularly in portable electronic equipment (such as mobile phones, laptops, and power tools), where they are gradually replacing nickel-cadmium (NiCd) and nickel-metal hydride (NiMH) batteries, and also in electric vehicles. They are also widely used to provide the power needed for new micro-applications, such as smart cards, sensors, and other electromechanical systems.

[0004] From a functional point of view, lithium-ion batteries operate on the principle of the intercalation-disintercalation of metallic ions within materials constituting the electrodes of the electrochemical cells of the battery, these materials being able to be described as (electrochemically) active materials.

[0005] More specifically, the reaction that produces current (i.e., when the battery is in discharge mode) involves the transfer, via an ionically conductive electrolyte, generally contained in a separator, of lithium cations from a negative electrode which intercalate into the acceptor network (or active material) of the positive electrode, while electrons from the reaction at the negative electrode supply the external circuit to which the positive and negative electrodes are connected.

[0006] The ionically conductive electrolytes used in lithium batteries can be of the liquid type, composed of organic solvent(s) in which one or more lithium salts are dissolved, or of the solid type, comprising one or more Lithium salts and one or more inorganic materials, such as sulfides, oxides, etc., or organic materials, such as polymers, are used in batteries. The composition of the ionically conductive electrolyte used in a battery has a significant impact on its performance. This performance is directly proportional to the ionic conductivity of the electrolyte, which ensures the mobility of ions between the positive and negative electrodes.

[0007] It is known that the use, in battery electrolytes, of lithium salts containing anions in which strong delocalization of negative charges occurs ensures good conduction of lithium ions through these electrolytes. Indeed, this strong delocalization weakens the ionic bond between the Li+ cation and its anion and consequently induces high mobility of the Li+ cation. Thus, the lithium salts commonly used in battery electrolytes have fluorinated groups, which are strong electron-withdrawers.This is particularly true of lithium bis(trifluoromethylsulfonyl)imidide (LiTFSI), a lithium salt widely used in flooded lithium batteries, as well as lithium bis(fluorosulfonyl)imidide (LiFSI), LiPF3(CF2CF3)3 (LiFAP), lithium trifluoromethanesulfonate LiCF3SO3 (LiTf), lithium fluorosulfonate LiSO3F, lithium hexafluorophosphate LiPF6, etc. However, the use of fluorinated anions significantly impacts the cost and end-of-life processing of the battery. Therefore, it appears advantageous to eliminate fluorine from the salts used in lithium battery electrolytes.

[0008] The same problem arises in the field of sodium batteries.

[0009] The present invention aims to provide an organic salt for lithium batteries or sodium, which gives the electrolyte in which it is integrated a high ionic conduction efficiency, allowing the formation of high-performance batteries, while being free of fluorine.

[0010] Additional objectives of the invention are that this organic salt be easy to prepare, and that it meet the economic, safety and environmental criteria currently expected for battery components intended for industrial or consumer use. Summary of the invention

[0011] It has now been discovered by the present inventors that these objectives are achieved by a salt corresponding to a specific chemical formula.

[0012] Thus, according to a first aspect, the present invention proposes an organic salt of alkali metal which is particularly suitable for use in a battery, more specifically a lithium battery or a sodium battery, which is free of fluorine atoms, and which corresponds to the general formula (I):

[0013] [Chem.l] NC' 1' GN M (I)

[0014] in which M represents an alkali metal selected from lithium and sodium.

[0015] Another aspect of the invention relates to a process for preparing an organic salt of alkali metal according to the invention, corresponding to the general formula (I) above, this process comprising successive steps of: - preparation of dicyano(naphthalene-l-sulfonyl)methane (NPDM) by reaction of naphthalene-l-sulfonyl chloride and malononitrile, in the presence of a tertiary amine, - purification of the dicyano(naphthalene-l-sulfonyl)methane thus obtained, - and contacting the dicyano(naphthalene-l-sulfonyl)methane thus purified with a hydride of said alkali metal.

[0016] This process may include a preliminary step of preparing naphthalen-l-sulfonyl chloride by chlorination of sodium 1-naphthalenesulfonate, by reaction of this compound with thionyl chloride.

[0017] An additional aspect of the invention lies in the use of an organic alkali metal salt according to the invention, corresponding to the general formula (I), this organic salt being in particular able to have been obtained by a process according to the invention, for the preparation of an electrolyte.

[0018] The invention also relates to a liquid electrolyte comprising an organic salt of alkali metal according to the invention, this organic salt being in particular obtained by a process according to the invention, and being dissolved in at least one organic solvent.

[0019] Another object of the invention is a solid electrolyte, comprising an organic salt of alkali metal according to the invention, this organic salt being in particular able to have been obtained by a process according to the invention, and at least one polymer.

[0020] In particular embodiments of the invention, this polymer comprises a repeating formula motif (II):

[0021] [Chem.2] O (II)

[0022] in which m is equal to 0, 1 or 2.

[0023] This is for example a poly(trimethylene carbonate) (PTMC), the ends of whose chain are preferentially devoid of free hydroxyl function.

[0024] Preferably, in such a polymer, the molar ratio "organic salt of alkali metal / carbonate groups of the polymer", expressed as a molar ratio [M] / [CO3], where M represents the alkali metal chosen from lithium and sodium, is between 1 / 2 and 1 / 40.

[0025] An additional object of the invention is an electrochemical cell for a battery, in particular a lithium battery or a sodium battery, comprising a positive electrode, a negative electrode, an electrolyte and where appropriate a separator disposed between said positive electrode and said negative electrode, and wherein said electrolyte is a liquid electrolyte according to the invention or a solid electrolyte according to the invention.

[0026] Another aspect of the invention relates to a battery, in particular a lithium battery or a sodium battery, comprising at least one electrochemical cell according to the invention.

[0027] The features and advantages of the invention will become more apparent in the light of the following detailed description and implementation examples, which are by no means limiting, of the invention, with the support of Figures 1 to 10. Brief description of the drawings

[0028] [Fig-1] Fig. 1 shows a schematic diagram of the synthesis of the organic lithium salt LiNPDM conforms to the invention.

[0029] [Fig.2] Fig.2 shows the characterization spectra of the intermediate compound naphthlen-1-sulfonyl chloride, in A / 'H NMR spectrum in CDC13, TMS (1%), in B / 13C NMR spectrum in CDC13, TMS (1%), and in C / Fourier transform infrared (FT-IR) spectroscopy spectrum.

[0030] [Fig. 3] [Fig. 3] shows the characterization spectra of the intermediate compound dicyano(naphthalene-l-sulfonyl)methane, in A / ¹H NMR spectrum in MeOD (and traces of acetone), in B / ¹³C NMR spectrum in MeOD (and traces of acetone), in C / Fourier transform infrared (FT-IR) spectroscopy spectrum, and in D / mass spectrum obtained by mass spectrometry with electrospray ionization (ESI) (negative mode).

[0031] [Fig.4] Fig.4 shows the characterization spectra of the organic lithium salt LiNPDM obtained according to the invention, in A / 'H NMR spectrum in MeOD, in B / 13C NMR spectrum in MeOD, and in C / Fourier transform infrared (FT-IR) spectroscopy spectrum.

[0032] [Fig. 5] Figure 5 shows the conductivity curves as a function of temperature, of liquid electrolytes containing, in a mixture EC:DMC (1:1), respectively the lithium organic salt LiNPDM according to the invention at 0.5 M, and the prior art compound LiTFSI at 0.5 M or 1 M.

[0033] [Fig. 6] Figure 6 shows the ¹H NMR spectrum of a PTMC polymer in CDC13 (and traces of dichloromethane).

[0034] [Fig.7] Figure [Fig.7] shows the ¹H NMR spectrum of an acetylated PTMC polymer in CDC13.

[0035] [Fig.8] Figure [Fig.8] shows the curves obtained by calorimetric analyses differential scanning (DSC) (at 10 K / min) for solid polymer electrolytes, respectively, PTMC / LiNPDM (according to the invention), and PTMC / LiTFSI (comparative example), the PTMC used being acetylated and having a number average molar mass of 2900 g / mol and each of the solid polymer electrolytes having a molar ratio [Li] / [CO3] = 1 / 15.

[0036] [Fig.9] Fig.9 shows the equivalent circuit used for data adaptation impedance for the determination by electrochemical impedance spectroscopy of the conductivity of solid polymer electrolytes.

[0037] [Fig. 10] Fig. 10 shows the conductivity curves, as a function of temperature, of solid polymer electrolytes, respectively, PTMC / LiNPDM (according to the invention), and PTMC / LiTFSI (comparative example), the PTMC used being acetylated and having an average number molar mass of 2900 g / mol and each of the solid polymer electrolytes having a molar ratio [Li] / [CO3] = 1 / 15. DETAILED DESCRIPTION

[0038] Organic salt of alkali metal

[0039] The alkali metal organic salt that is the subject of the invention, corresponding to the general formula (I) above, is a lithium salt or a sodium salt. It may thus correspond to formula (la) or formula (Ib) below:

[0040] [Chem.3] NC"' S '"XN Li (there)

[0041] [Chem.4] o=s=o NC" x.CN Na" (Ib).

[0042] The anion of the alkali metal organic salt according to the invention is advantageously non-fluorinated, which remedies the problem of the impact on the cost and end-of-life treatment of batteries associated with the use of fluorinated anions in the salts used therein. Furthermore, unlike fluorinated salts of the prior art, the preparation of the alkali metal organic salt according to the invention advantageously does not use any per- or polyfluoroalkylated substances, the toxicity and harmful effects of which on health and the environment are widely recognized.

[0043] Furthermore, this organic salt, used in an electrolyte within a battery, exhibits performance close to that obtained with the prior art fluorinated salt bis(trifluoromethylsulfonyl)imidide of the same alkali metal. By way of example, the ionic conductivity of a liquid electrolyte formed from an equivolume mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC), comprising the organic salt according to the invention, in which M represents lithium, at a concentration of 0.5 M, was measured by the present inventors at 3.1 mS.cm⁻¹ at 20°C, compared to 7.4 mS.cm⁻¹ at the same temperature for a similar electrolyte containing the prior art lithium salt LiTFSI. The ionic conductivity of a solid electrolyte formed from a poly(trimethylene carbonate) polymer (PTMC), comprising the organic salt according to the invention, in which M represents lithium, has for its part was measured by the present inventors at a value of 1.7.103 mS.cm 1 at 80°C, compared to 6.3.103 mS.cm 1 at the same temperature for a similar electrolyte containing the lithium salt LiTFSI of the prior art.

[0044] Thus, the organic salt according to the invention appears as a particularly interesting fluorine-free alternative to replace prior art fluorinated salts in battery electrolytes.

[0045] We will not speculate here on the mechanisms underlying the achievement of such good performance, in terms of ionic conductivity, of the organic salt according to the invention. However, it can be assumed that this performance results from the specific formula of the anion constituting this salt. Indeed, the particular conjugation system existing within this anion leads to a strong delocalization of the negative charge, partly attributable to the presence of the strongly electron-withdrawing groups, namely the cyano-CN groups, conjugated to the sulfonyl group and the naphthalene ring. It follows that the ionic bond between the Li+ or Na+ cation and its anion is greatly weakened, so that this cation, weakly coordinated to the anion, is particularly mobile.

[0046] Process for preparing the organic alkali metal salt

[0047] The alkali metal organic salt according to the invention can be obtained by any synthetic route the development of which falls within the competence of a person skilled in the art.

[0048] However, the present inventors have discovered that a particularly high yield can be obtained by a preparation process comprising successive steps of: - preparation of dicyano(naphthalene-l-sulfonyl)methane (NPDM), with general formula (inc):

[0049] [Chem.5] O=$^O IMCX (IIIc)

[0050] by reaction of naphthalene-l-sulfonyl chloride, of formula (Illb):

[0051] [Chem.6]

[0052]

[0053] (Illb) and malononitrile, formula (IV): [Chem.7]

[0054]

[0055]

[0056] (IV) in the presence of a tertiary amine, - purification of the dicyano(naphthalene-l-sulfonyl)methane thus obtained, - and contacting the purified dicyano(naphthalene-l-sulfonyl)methane with an alkali metal hydride: lithium hydride LiH or sodium hydride NaH depending on the specific alkali metal organic salt targeted. The naphthalene-1-sulfonyl chloride of formula (Illb) above may have been obtained by any conventional method in itself. In particular embodiments of the invention, the process includes a preliminary step of preparing the naphthalene-1-sulfonyl chloride by chlorination, by reaction with thionyl chloride, of sodium 1-naphthalenesulfonate, of general formula (Ilia): [Chem. 8]

[0057]

[0058] SOiNa (Ilia). This chlorination reaction can be carried out in an aprotic solvent, preferably polar, such as dimethylformamide. It is preferably performed at room temperature, i.e., between approximately 18 and 25 °C, and for a duration of a few hours, specifically between 2 and 24 hours. The process according to the invention preferably includes a step of separating the naphthalen-l-sulfonyl chloride thus obtained from the reaction medium, for example by precipitation in water and filtration, and preferably a purification step of this compound, for example by sublimation after drying.

[0059] The step of preparing dicyano(naphthalene-l-sulfonyl)methane (NPDM), of formula (IIIc), from naphthalene-l-sulfonyl chloride of formula (Illb), is advantageously carried out by introducing the dicyanomethyl motif onto the sulfonyl group of the latter by nucleophilic substitution. This reaction is carried out in the presence of a non-nucleophilic tertiary amine, such as triethylamine, 1,4-diazabicyclo[2.2.2]octane (DABCO), or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), DBU being particularly preferred in the context of the invention because it allows for a higher reaction yield.

[0060] This reaction is preferably carried out in an aprotic solvent, preferably polar, such as acetonitrile. It is preferably carried out at room temperature, and for a period of a few hours, in particular between 6 and 24 hours.

[0061] The purification step of the dicyano(naphthalene-l-sulfonyl)methane thus obtained can be carried out in any conventional manner. In particular, it can be carried out by drying the reaction medium, introducing the residue into ethyl acetate, and washing the organic phase with an acidic aqueous solution, for example, hydrochloric acid, and then, optionally, with a neutral aqueous solution, for example, sodium chloride. Optionally, the process according to the invention can then include steps of concentrating the organic phase, introducing it into an aprotic solvent, preferably polar, such as dichloromethane, and isolating the resulting dicyano(naphthalene-l-sulfonyl)methane precipitate, preferably by filtration.

[0062] The final synthesis step of the process according to the invention, starting from dicyano(naphthalene-l-sulfonyl)methane, is carried out by contacting this compound with the alkali metal hydride. This contacting is preferably carried out in an aprotic solvent, preferably polar, such as tetrahydrofuran. It is preferably carried out at room temperature, and for a period of a few hours, in particular between 1 and 24 hours.

[0063] This third synthesis step is preferably followed by a purification step of the organic salt of general formula (I) obtained, for example by filtering the reaction medium so as to remove the excess of alkali metal hydride, preferably followed by a drying step.

[0064] The process according to the invention, meeting one or more of the characteristics described above, advantageously makes it possible to obtain the alkali metal organic salt according to the invention in a simple manner, in only three synthesis steps, and with a high yield and a high level of purity.

[0065] The alkali metal organic salt according to the invention can find application in various electrochemical systems, in particular in energy storage systems, especially batteries, of the lithium or sodium type, within an electrolyte composition contained in such systems.

[0066] Electrolyte composition

[0067] Thus, the organic alkali metal salt according to the invention, this organic salt being in particular obtained by a process according to the invention, meeting one or more of the above characteristics, can advantageously be used for the preparation of an electrolyte, in particular intended for use in a lithium battery or a sodium battery, depending on whether the alkali metal entering into the constitution of the organic salt is, respectively, lithium or sodium.

[0068] This electrolyte can be either liquid or solid. In particular, it may include one or more of the characteristics described below with reference to the electrolytes according to the invention.

[0069] An object of the present invention is an electrolyte, in particular intended for use in a lithium battery or a sodium battery, comprising an organic alkali metal salt according to the invention, of general formula (I), in particular as obtained by a preparation process according to the invention, meeting one or more of the characteristics stated above.

[0070] In variants of the invention, the electrolyte is of the liquid type, and it comprises an organic salt of alkali metal according to the invention, in particular an organic salt such as is obtained by a preparation process according to the invention, this salt being dissolved in an organic solvent or in a mixture of several organic solvents.

[0071] Any organic solvent conventionally used in liquid electrolyte formulations for batteries can be used within the scope of the invention. Examples of such organic solvents include carbonate-type solvents, such as: - cyclic carbonate solvents, such as ethylene carbonate (EC), propylene carbon (PC), butylene carbonate, vinylene carbonate, fluoroethylene carbonate and fluoropropylene carbonate, - linear carbonate solvents, such as diethyl carbonate (DEC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC), - or any mixture thereof; or ester-type solvents, such as ethyl propionate and n-propyl propionate, nitrile-type solvents, such as acetonitrile, or ether-type solvents, such as dimethyl ether and 1,2-dimethoxyethane.

[0072] By way of example, the composition of the liquid electrolyte according to the invention may comprise a mixture, preferably equivolumetric, of ethylene carbonate and dimethyl carbonate.

[0073] The alkali metal organic salt according to the invention can be contained in the liquid electrolyte composition at a concentration between 0.1 M and 2 M, preferably between 0.5 and 1.5 M.

[0074] The composition of the liquid electrolyte may also contain one or more conventional additives, particularly those intended to improve its performance, stability and / or safety. Examples of such additives include fluoroethylene carbonate (FEC) or vinylene carbonate (VC).

[0075] In alternative embodiments of the invention, the electrolyte is in solid form, and comprises an organic salt of alkali metal according to the invention, in particular an organic salt such as is obtained by a preparation process according to the invention, this organic salt being combined with one or more polymers.

[0076] The solid electrolyte according to the invention is preferably of the type intended to form a solid polymeric electrolyte (SPE) or a hybrid solid electrolyte (HSE).

[0077] In the present description, a solid electrolyte is understood, in a classical sense, as an electrolyte devoid of liquid components, and capable of acting, in an electrochemical cell, as both an ionic conductor and a separator, preventing the electrodes from coming into physical contact with each other.

[0078] The composition of the solid electrolyte according to the invention may further contain any conventional additive in itself in the field of SPE or HSE electrolyte batteries, such as an inorganic charge conductive of the alkali metal cation of the organic salt.

[0079] The solid electrolyte according to the invention can be prepared according to any conventional method in itself for a person skilled in the art.

[0080] According to variations of the invention, it can be prepared by solvent preparation, the alkali metal organic salt according to the invention, the polymer(s) and any additives being brought into contact in an organic solvent or a mixture of organic solvents, preferably aprotic and preferably polar, for example acetonitrile or tetrahydrofuran. The contact can be carried out at a temperature between 30 and 70°C, for example around 50°C, for a period of between 12 and 24 hours. This is followed by an evaporation step of the solvent(s) used, in particular under reduced pressure, at a temperature ensuring such evaporation.

[0081] According to other embodiments of the invention, the solid electrolyte can be prepared by melting, in the absence of solvents. In such embodiments, the alkali metal organic salt according to the invention, the polymer(s) and any additives are heated to a temperature above the glass transition temperature of each of the polymers, and mixed when each polymer is in a molten state, the mixture is then cooled to cause it to solidify.

[0082] The composition of the solid electrolyte according to the invention may contain any conventional polymer in itself. In this description, the term polymer encompasses both polymers strictly speaking, that is to say formed of a single repeating unit, and copolymers, comprising several different repeating units.

[0083] The polymer or polymers forming part of the solid electrolyte composition according to the invention may, for example, be of the polyether type, such as poly(oxyethylene) (POE) and its derivatives.

[0084] Preferably, the polymer or polymers used in the composition of the solid electrolyte according to the invention belong to the family of aliphatic polycarbonates, and more particularly to poly(alkylene carbonate).

[0085] In preferred embodiments of the invention, at least one, preferably each, polymer forming part of the composition of the solid electrolyte according to the invention comprises a repeating pattern of formula (II):

[0086] [Chem.2] (II)

[0087] in which m is equal to 0, 1 or 2, and preferably equal to 1.

[0088] This repeating unit (also called the monomer unit) may be the only repeating unit of the polymer, the latter then belonging to the poly(alkylene carbonate) family, and preferably comprising from 10 to 100 repeats of the repeating unit of formula (II). Preferably, the polymer is a poly(trimethylene carbonate) (PTMC), m being equal to 1 in formula (II), this PTMC preferably comprising from 10 to 100 repeats of the repeating unit of formula (II).

[0089] Alternatively, the polymer entering into the composition of the solid electrolyte according to the invention may be a copolymer, comprising a monomer unit of formula (II), and at least one different monomer unit, for example of e-caprolactone, and / or several units of different formula (II), i.e. having different m values.

[0090] Polymers of the poly(trimethylene carbonate) family, used in a solid electrolyte for lithium batteries, offer in particular the advantages of allowing access to a wide electrochemical stability window (up to 4.5 V vs. Li / Li+), to exhibit good thermal stability and a high ion transport number (t+ = 0.75).

[0091] The poly(alkylene carbonate), in particular PTMC, implemented according to the invention can be obtained by any synthetic method known to those skilled in the art, for example by ring-opening polymerization reaction of the corresponding alkylene carbonate, in particular trimethylene, in the presence of a polymerization reaction initiator, and optionally a catalyst such as diphenyl phosphate. Examples of such processes are described in particular in document FR 3130454, or below in this description.

[0092] In particularly preferred embodiments of the invention, the poly(alkylene carbonate), in particular PTMC, is devoid of free hydroxyl groups at the end of the chain.

[0093] The poly(alkylene carbonate), in particular PTMC, which is part of the composition of the solid electrolyte according to the invention, then preferably corresponds to the general formula (V):

[0094] [Chem.9] (V)

[0095] in which n is an integer preferably between 10 and 100, m is equal to 0, 1 or 2, preferably equal to 1, and X and Y, identical or different, each represent a group devoid of a free hydroxyl function.

[0096] Depending on the method used to synthesize poly(alkylene carbonate), in particular PTMC, X may be a group from a single hydroxyl function initiating polymerization reaction compound, for example 3-phenyl-l-propanol, or consist of a hydroxyl function protecting group.

[0097] Y preferably consists of a protecting group of a hydroxyl function.

[0098] A protecting group of a hydroxyl function is understood to mean any group used in a conventional way on its own to protect a hydroxyl group, that is, to mask its reactivity. It falls within the competence of a person skilled in the art to identify hydroxyl group-protecting groups that can be used in the context of the invention. Examples of such groups Protective groups are notably listed in Greene's book, "Protective groups in Organic Synthesis", (4th ed.) Wiley & Sons, 2006.

[0099] Each of the protecting groups of a hydroxyl function implemented according to the invention can for example be chosen from among the alkyl, acyl groups, in particular acetyl, benzyl, silyl, sulfonyl, alkoxy-alkyl, for example methoxymethyl, methoxyethoxymethyl or benzoxymethyl, etc.

[0100] X and / or Y can in particular be obtained by reaction of poly(alkylene carbonate), in particular PTMC, with a compound selected from acyl chlorides, such as benzoyl chloride and acetyl chloride, acid anhydrides, such as acetic anhydride, and isocyanates, such as p-tolenesulfonyl isocyanate.

[0101] It is within the competence of a person skilled in the art to determine the reaction conditions enabling the protection of the free hydroxyl groups of poly(alkylene carbonate), in particular of PTMC, according to the protecting group of a desired hydroxyl function.

[0102] By way of example, the composition of the solid electrolyte according to the invention may comprise a poly(alkylene carbonate), in particular a PTMC, corresponding to the general formula (Va):

[0103] [Chem. 10] (Go)

[0104] in which n is preferably an integer between 10 and 100, and m is equal to 0, 1 or 2, preferably equal to 1.

[0105] In particular embodiments of the invention, at least one poly(alkylene carbonate), in particular PTMC, preferably all of these polymers, entering into the composition of the solid electrolyte, has a number average molar mass of less than 10,000 g / mol, and preferably greater than or equal to 1,000 g / mol and preferably greater than or equal to 1,500 g / mol.

[0106] The number-average molar mass can, for example, be determined by size-exclusion chromatography, possibly coupled with static light scattering. This determination falls within the basic skills of a person skilled in the art.

[0107] In particular embodiments of the invention, the molar ratio "alkali metal organic salt of formula (I) / carbonate groups of poly(alkylene carbonate), in particular of the PTMC polymer", in the solid electrolyte, expressed as a molar ratio [M] / [CO3], is between 1 / 2 and 1 / 40, preferably between 1 / 5 and 1 / 25, and for example equal to 1 / 15.

[0108] In the particular configurations of the invention in which the alkali metal M entering into the constitution of the organic salt is lithium, the molar ratio "organic lithium salt / carbonate groups of poly(alkylene carbonate), in particular of the PTMC polymer", in the solid electrolyte, expressed as a molar ratio [Li] / [CO3], is thus preferably between 1 / 2 and 1 / 40, preferably between 1 / 5 and 1 / 25, and for example equal to 1 / 15.

[0109] The polymer or polymers forming part of the solid electrolyte according to the invention may be crosslinked or non-crosslinked.

[0110] The solid electrolyte according to the invention can be shaped into a film or membrane, which can be used directly within an electrochemical battery cell.

[0111] This shaping can be carried out at the end of the electrolyte preparation process, before the step of transitioning to the solid state, by depositing the electrolyte composition in the fluid state on the surface of a suitable substrate, preferably flat in shape, and then solidification.

[0112] By way of example, in embodiments where the solid electrolyte is formed by solvent extraction, deposition on the substrate surface can advantageously be carried out before the evaporation step of the solvent(s), for example by coating. In embodiments where the solid electrolyte is formed by melt extraction, deposition on the substrate surface can advantageously be carried out on the molten electrolyte composition, for example by extrusion, before the cooling step. All of these techniques are well known to those skilled in the art.

[0113] The substrate used is then chosen from among substrates made of materials that are chemically inert with respect to the components of the solid electrolyte, for example glass, silicone, polytetrafluoroethylene (PTFE), polypropylene, etc.

[0114] After solidification, the resulting film or membrane may or may not be detached from the substrate for its subsequent use.

[0115] Electrochemical cell

[0116] The electrolytes according to the invention, whether in liquid or solid form, are particularly suitable for use in an electrochemical cell for batteries, more specifically lithium batteries or batteries sodium according to the alkali metal entering into the constitution of the organic salt of alkali metal contained in the electrolyte according to the invention.

[0117] Thus, the present invention also relates to the use of a liquid electrolyte or a solid electrolyte according to the invention for the manufacture of an electrochemical cell for a battery, more specifically a lithium battery or a sodium battery, said electrolyte being included in, and preferably constituting, the electrolyte of such an electrochemical cell.

[0118] A further aspect of the invention is an electrochemical battery cell comprising a positive electrode, a negative electrode, an electrolyte, and optionally a separator disposed between the positive and negative electrodes. This electrolyte is a liquid electrolyte according to the invention or a solid electrolyte according to the invention.

[0119] In the present description, the positive electrode is understood to be, in a classical sense, the electrode which acts as the cathode when the electrochemical cell is delivering current (i.e., when it is in the process of discharging) and which acts as the anode when the electrochemical cell is in the process of charging.

[0120] By negative electrode, we mean, also in a classical way in itself, the electrode which acts as an anode when the electrochemical cell delivers current (that is to say when it is in the process of discharging) and which acts as a cathode when the battery cell is in the process of charging.

[0121] The electrodes of the electrochemical cell according to the invention can be formed from any conventional material in itself for this type of application.

[0122] By way of example, for a lithium electrochemical cell: - the positive electrode may comprise, as electrochemically active material, lamellar compounds, such as LiCoO2, LiNiO2 and mixed Li(Ni,Co,Mn,Al)O2, or spinel structure compounds with compositions close to LiMn2O4, lithium phosphates, in particular LiMnFePO4 or LiFePO4, etc. - the negative electrode may include, as an electrochemically active material, lithium metal or a lithium-based alloy, intercalation materials such as graphite, lithium titanium oxide (Li4Ti50i2), silicon, graphite / silicon composites, etc.

[0123] Each of the electrodes of the electrochemical cell can be associated with a current collector.

[0124] The separator, when implemented, particularly in embodiments where the electrolyte according to the invention is in liquid form, can be of any type conventionally used in electrochemical cells for lithium batteries or sodium, for example consisting of a porous polyethylene film, such as a Celgard® type film, in particular sandwiched between two layers of polypropylene.

[0125] In particular embodiments of the invention in which the electrolyte is in solid form, the electrolyte is preferably in the form of a film or membrane, sandwiched between the positive electrode and the negative electrode, this film or membrane being able to further act as a separator between these electrodes.

[0126] Battery

[0127] The electrochemical cells according to the invention can be implemented within a lithium or sodium battery, depending on the alkali metal entering into the constitution of the organic alkali metal salt according to the invention.

[0128] Thus, an object of the invention is a lithium battery, for example a lithium-ion or lithium-metal battery, comprising one, preferably several, electrochemical cells according to the invention, in which the organic salt contained in the composition of the electrolyte corresponds to the formula (la), that is to say comprises Li+ as a cation.

[0129] Another object of the invention is a sodium battery, for example a sodium-ion or sodium-metal battery, comprising one, preferably several, electrochemical cells according to the invention, in which the organic salt contained in the composition of the electrolyte corresponds to the formula (Ib), that is to say comprises Na+ as a cation.

[0130] The batteries according to the invention can be in any conventional form in itself, in particular have a planar type format, for example button cell type, a cylindrical format, in particular an AAA, AA, C, D or DD format, a wound or spiral format, a prismatic format, etc.

[0131] The following implementation examples are provided for illustrative purposes only and are in no way limiting of the invention. EXAMPLES

[0132] Materials and methods

[0133] Commercial reagents were used without further purification, except for malononitrile, which was purified by sublimation. Sodium 1-naphthalenesulfonate was purchased from Fisher Scientific. The other reagents and solvents were purchased from Sigma-Aldrich. The reactions were carried out under an inert atmosphere (argon), unless explicitly stated otherwise. The 1H and 13C NMR spectra were acquired on a Bruker NEO 400MHz spectrometer equipped with a 5 mm BBO Smart Probe. The spectra were referenced to the solvent peak. The infrared spectra were recorded with a PerkinElmer Spectrum Two® Fourier transform infrared (FT-IR) spectrometer. Mass spectrometry analyses were performed using an Agilent 6230 series LC-MS / TOF unit. CHNS elemental analyses were performed using an Elementar Unicube® organic elemental analyzer. Differential scanning calorimetry (DSC) analyses were performed with a Netzsch DSC 404 Fl Pegasus® calorimeter and 40 pL low-pressure aluminum crucibles, at 10 K / min under helium.

[0134] 1 / Example 1 - Synthesis of LiNPDM

[0135] Dicyano(naphthalene-l-sulfonyl)methyllithium (LiNPDM) is prepared according to the reaction scheme shown in [Fig. 1], in several steps.

[0136] 1.1 / Step 1 - Synthesis of naphthalen-l-sulfonyl chloride

[0137] The intermediate compound naphthalen-l-sulfonyl chloride, of formula (Illb):

[0138] [Chem. 11] 0™S—O (iiib)

[0139] is prepared as follows.

[0140] In a three-necked flask under argon, thionyl chloride (15 mL, 199.6 mmol, 2.3 eq.) is added dropwise with stirring to a solution of sodium 1-naphthalenesulfonate (20 g, 86.9 mmol, 1 eq.) in anhydrous dimethylformamide (DMF) (80 mL) that has been previously cooled to 0°C. Once the addition is complete, the reaction mixture is allowed to return to room temperature (Tamb) and stirred for 18 h. The reaction mixture is then added dropwise to cold distilled water, and the resulting precipitate is filtered through a sintered filter and dried under vacuum. The collected brown solid is purified by sublimation to give a white solid (17.656 g, Yield = 90%).

[0141] The 'H NMR, 13C NMR and FT-IR spectra of the compound obtained are shown in [Fig.2], respectively in A / , B / and C / . 'H NMR (400 MHz, CDC13): ô (ppm): 8.79 (d, 'J = 8.8 Hz, 1H, H8), 8.36 (d, 'J = 7.4 Hz, 1H, H2), 8.21 (d, 3 J = 8.2 Hz, 1H, H4), 8.00 (d, 3 J = 8.2 Hz, 1H, H5), 7.80 (ddd, 3 J = 7.4 Hz, 3 J = 8.8 Hz, 4 J = 1.4 Hz, 1H, H7), 7.68 (ddd, 3 J = 7.2 Hz, 3 J = 8.2 Hz, 4 J = 1.1 Hz, 1H, H6), 7.59 (dd, 3 J = 7.4 Hz, 3 J = 8.2 Hz, 1H, H3). (Assigned with a COSY spectrum) 13C{H} NMR (100 MHz, CDC13): ô (ppm): 139.6 (Cl), 137.1 (C4), 134.5 (CIO), 129.6 (C7), 129.5 (C2), 129.4 (C5), 127.9 (C6), 127.5 (C9), 124.2 (C8), 124.0 (C3). (Assigned with an HSQC spectrum) FT-IR (cm1): 3063 (vC H), 1590 (vc=c), 1560, 1506 (vc=c), 1361 (vs=o), 1172 (vs=o), 1138 (vs=o), 969, 866, 830, 803, 767(vc.H), 674, 624, 577, 506. Calculated for Ci0H7C1O2S: C 52.99, H 3.11, S 14.14%; Found: C 52.92, H 2.98, S 14.13%

[0142] 1.2 / Step 2 - Synthesis of dicyano(naphthalene-l-sulfonyl)methane

[0143] The intermediate compound dicyano(naphthalene-l-sulfonyl)methane (NPDM), of formula (IIIc):

[0144] [Chem. 12] (IIIc)

[0145] is prepared as follows.

[0146] In a two-necked argon-filled round-bottom flask, a solution of naphthalen-l-sulfonyl chloride (5.0 g, 22.1 mmol, 1 eq.) in anhydrous tacetonitrile (20 mL) is added dropwise, with stirring, to a solution of malononitrile (1.46 g, 22.1 mmol, 1 eq.) in anhydrous tacetonitrile (ACN) (15 mL) that has been previously cooled to 0°C. Once the addition is complete, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (8.0 g, 55.3 mmol, 2.5 eq.) is added to the reaction mixture. The mixture is then allowed to return to room temperature and stirred for 22 hours. The reaction mixture is then concentrated under vacuum and resuspended in ethyl acetate. The organic phase is extracted three times with an aqueous HCl solution (IM) and once with a saturated NaCl solution. The organic phase is dried over MgSO4, filtered, and concentrated under vacuum.The crude reaction mixture is diluted and triturated in dichloromethane; the resulting brown precipitate is isolated by filtration on sintered material (3.11 g, Yield = 61%).

[0147] The 'H NMR, 13C NMR, FT-IR and ESI mass spectra of the compound obtained are shown in [Fig.3], respectively in A / , B / , C / and D / . 'H NMR (400 MHz, MeOD): ô (ppm): 8.78 (d, 3 J = 8.3 Hz, 1H, H8), 8.17 (d, 3 J = 7.4 Hz, 1H, H2), 8.08 (d, 3 J = 8.1 Hz, 1H, H4), 7.99 (d, 3 J = 8.0 Hz, 1H, H5), 7.66 (dd, 3 J=8.3 Hz, 3 J = 7.3 Hz, 1H, H7), 7.60 (dd, 3 J = 8.0 Hz, 3 J = 7.3 Hz, 1H, H6), 7.55 (dd, 3 J = 8.1 Hz, 3 J = 7.4 Hz, 1H, H3). 13C{H} NMR (100 MHz, MeOD): ô (ppm): 141.9 (Cl), 136.0 (CIO), 134.3 (C4), 129.9 (C5), 129.3 (C9), 128.6 (C7), 128.5 (C2), 127.7 (C6), 126.8 (C8), 125.2 (C3), 121.1 (C12), 44.4 (Cil). (Assigned with an HSQC spectrum) FT-IR (cm1): 3482-3414 (vC H), 3063 (vc.H(Ar)), 2201 (vc,N), 2173 (vc,n), 1701, 1508 (vc=c), 1298 (vs=o), 1125 (vs=o), 762 (vC H), 689, 649, 583, 580, 528. MS (ESI): m / z: [MH] = 255.0, [2(MH)+Na] = 533.0.

[0148] 1.3 / Step 3 - LiNPDM Synthesis

[0149] LiNPDM, of formula (la):

[0150] [Chem. 13] 4 hi (there)

[0151] is prepared as follows.

[0152] In a two-necked argon-filled flask, a solution of NPDM (2.8 g, 10.9 mmol, 1 eq.) in anhydrous THF (30 mL) is added dropwise, with stirring, to a suspension of lithium hydride (LiH) (95.1 mg, 12.0 mmol, 1.1 eq.) in anhydrous tetrahydrofuran (THF) (30 mL), previously prepared in a glove box and cooled to 0°C. Once the addition is complete, the reaction mixture is allowed to return to room temperature and stirred for 19 h. The reaction mixture is then filtered through a sintered filter to remove excess lithium hydride and subsequently dried under vacuum to give a white solid corresponding to LiNPDM (2.26 g, Yield = 79%).

[0153] The 'H NMR, 13C NMR and FT-IR spectra of the compound obtained are shown in [Fig.4], respectively in A / , B / and C / . NMR 'H (400 MHz, MeOD) : ô (ppm) : 8.78 (d, 3 J= 8.3 Hz, 1H, H8), 8.17 (d, 3 J = 7.4 Hz, 1H, H2), 8.08 (d, 3 J = 8.1 Hz, 1H, H2), 8.08 (d, 3 J = 8.1 Hz, 1H, H2), Hz, 1H, H5), 7.66 (dd, 3 J = 8.3 Hz, 3 J = 7.3 Hz, 1H, H7), 7.60 (dd, 3 J = 8.0 Hz, 3 J = 7.3 Hz, 1H, H6), H3). NMR 13C{H} (100 MHz, MeOD) : O (ppm) : 141.9 (Cl), 136.0 (CIO), 134.3 (C4), 129.9 (C5), 129.3 (C9), 128.6 (C7), 128.5 (C2.2), 127 (C7), 6.6. (C8), 125.2 (C3), 121.1 (C12). (Assigned with an HSQC spectrum) FT-IR (cm1): 3063 (vc.H(Ar)), 2205 (vc,N), 2174 (vc,N), 1506 (vc=c), 1304 (vs=o), 1123 (Vs=o), 774 (vc.h), 691, 651, 608, 725, 258.

[0154] 2 / Example 2 - Liquid electrolytes

[0155] 2.1 / Preparation

[0156] Liquid electrolytes are prepared by dissolving, in a mixture of ethylene carbonate (EC): dimethyl carbonate (DMC) (1:1 v / v), the following salts: - LiNPDM obtained in Example 1, at 0.5 M, - LiTFSI at 1 M or 0.5 M.

[0157] 2.2 / Conductivity measurement

[0158] Electrochemical impedance spectroscopy (EIS) measurements are performed on a BioLogic VMP-300 potentiostat, between 60°C and 10°C, temperatures in decreasing steps of 10°C (stabilization of 2H at each step), in a BioLogic Platinized HTCC conductivity cell placed in an oven.

[0159] The conductivity of the electrolyte is calculated using Equation (1):

[0160] [Math.l] (1)

[0161] in which: o is the conductivity of the electrolyte (S / cm), R is the resistance of the electrolyte (Q) and k is the cell constant (0.88 cm1).

[0162] The results obtained are shown in [Fig.5]. It can be observed that the LiNPDM-based electrolyte according to the invention exhibits good conductivity compared to LiTFSI-based electrolytes at low salt levels.

[0163] 3 / Example 3 - Polymer electrolytes

[0164] 3.1 / Polymer preparation

[0165] The polymer used in this example is acetylated poly(trimethylene carbonate) (PTMC), prepared according to the following 2 steps.

[0166] a / PTMC Synthesis

[0167] The PTMC, with the formula:

[0168] [Chem. 14]

[0169] is prepared as follows.

[0170] In a two-necked flask under argon, trimethylene carbonate (25 g, 0.245 mol, 24.5 eq.), anhydrous dichloromethane (80 mL), and 3-phenyl-l-propanol (1.3 mL, 0.010 mol, 1 eq.) are added. A solution of diphenyl phosphate (1.96 g, 0.008 mol, 0.8 eq.) in dichloromethane (20 mL) is added to the reaction mixture while stirring. After 48 h at room temperature, the reaction mixture is neutralized with triethylamine (1.4 mL, 0.010 mol, 1 eq.). The reaction medium is concentrated under vacuum and the product obtained is precipitated in cold methanol and dried under vacuum at 60°C to give PTMC (26.3 g, 2800 g / mol, Yield = 98%).

[0171] The H NMR spectrum of the compound obtained is shown in [Fig.6]. 'H NMR (400 MHz, CDC13): ô (ppm): 1.91 (q, 4H, H5, H8), 2.05 (q, 50H, H2), 2.71 (t, 2H, H9), 3.73 (t, 2H, H4), 4.15 (t, 2H, H7), 4.24 (t, 100H, Hl, H3), 4.29 (t, 2H, H6), 7.18-7.30 (m, 5H, H^).

[0172] b / PTMC Acetylation

[0173] Acetylated PTMC, of ​​formula (Vb):

[0174] [Chem. 15] oo (Vb)

[0175] in which n is preferably between 10 and 100, is prepared as follows.

[0176] In a two-necked flask under argon, acetyl chloride (1.3 mL, 17.7 mmol, 5 eq.) is added dropwise to a solution of PTMC (10 g, 3.53 mmol, 1 eq.) and triethylamine (2.5 mL, 17.7 mmol, 5 eq.) in dichloromethane (40 mL). After 18 h of reaction, the product is precipitated in cold methanol and dried under vacuum to give acetylated PTMC (9.52 g, Yield = 94%), with a number-average molar mass of 2900 g / mol.

[0177] The H NMR spectrum of the compound obtained is shown in [Fig.7].

[0178] 3.2 / Preparation of polymer electrolytes

[0179] a / PTMC / LiNPDM polymer electrolyte

[0180] The PTMC / LiNPDM polymer electrolyte according to the invention is prepared as follows.

[0181] In a glove box, acetylated PTMC prepared as described in the previous section (2900 g.mol⁻¹, 1.50 g, 0.52 mmol, 1 eq.), LiNPDM (0.246 g, 0.92 mmol, 1.76 eq.), and anhydrous acetonitrile (5 mL) are successively introduced into a bottle. The mixture is stirred at 50°C for 15 hours. The acetonitrile is then evaporated, and the electrolyte is dried at 80°C under vacuum for 96 hours. The electrolyte is stored in a glove box.

[0182] It has a molar ratio [Li] / [CO3] = 1 / 15.

[0183] b / PTMC / LiTFSI polymer electrolyte

[0184] The PTMC / LiTFSI polymer electrolyte (comparative example) is prepared as follows.

[0185] In a glove box, acetylated PTMC prepared as described in the previous section (2900 g.mol⁻¹, 1.50 g, 0.52 mmol, 1 eq.), LiTFSI (0.264 g, 0.92 mmol, 1.76 eq.), and anhydrous THF (5 mL) are successively introduced into a bottle. The mixture is stirred at 50°C for 15 hours. The THF is then evaporated, and the electrolyte is dried at 80°C under vacuum for 96 hours. The electrolyte is stored in a glove box.

[0186] It has a molar ratio [Li] / [CO3] = 1 / 15.

[0187] 3.3 / Analysis by differential scanning calorimetry

[0188] Polymer electrolytes are subjected to analysis by DSC.

[0189] The curves obtained are shown in [Fig.8]. The following glass transition temperature values ​​are deduced: - PTMC / LiNPDM: Tg = - 21.6°C, - PTMC / LiTFSI: Tg = - 14.5°C.

[0190] 3.4 / Measurement of conductivity

[0191] The polymer electrolytes prepared above are inserted into button cells, in the form of symmetrical cells with blocking stainless steel electrodes. Within these cells, the electrolyte to be tested is placed as a thin film in the center of a polyethylene disc with an external diameter of 16 mm and an internal diameter of 10 mm, the assembly being held under pressure between the two disc-shaped stainless steel electrodes.

[0192] The button cells are then placed in an oven at 80°C. After 3 hours of equilibrium, electrochemical impedance spectroscopy (EIS) measurements are performed on a BioLogic VMP-300 potentiostat, between 80°C and 10°C, with temperatures decreasing in 10°C increments (2 hours of stabilization at each increment). Three button cells are prepared for each electrolyte.

[0193] The conductivity of the electrolyte is calculated using Equation (2):

[0194] [Math.2] £ {J - ------- 5 X (2)

[0195] in which: o is the conductivity of the electrolyte (S / cm), e is the thickness of the electrolyte (cm), S is the surface area of ​​the electrolyte (cm2) and R2 is the resistance of the electrolyte (Q), after fitting the data with the equivalent circuit shown in [Fig.9]. In this figure, block 11 represents the resistance of the cables and the battery holder (“RI”), block 12 represents the contribution of the ionic conductivity of the material (“R2”) and element 13, connected in parallel with R2, represents the constant phase element or CPE (“Q2”).

[0196] The results obtained are shown in [Fig. 10]. It can be observed that the conductivities of the PTMC-LiNPDM and PTMC-LiTFSI polymer electrolytes are similar. Indeed, the conductivity measured during this study is, at 80°C, 1.7 x 10³ mS·cm⁻¹ for the PTMC-LiNPDM polymer electrolyte system, compared to 6.3 x 10³ mS·cm⁻¹ for the PTMC-LiTFSI system. Thus, LiNPDM appears to be an interesting fluorine-free alternative to LiTFSI.

Claims

1. Demands Organic salt of alkali metal of general formula (I): [Chem. 1]

2.

3.

4.

5.

6.

7. in which M represents an alkali metal chosen from lithium and sodium. A process for preparing an organic alkali metal salt according to claim 1, comprising successive steps of: - preparation of dicyano(naphthalene-l-sulfonyl)methane by reaction of naphthalene-l-sulfonyl chloride and malononitrile in the presence of a tertiary amine, - purification of the dicyano(naphthalene-l-sulfonyl)methane thus obtained, - and contacting dicyano(naphthalene-l-sulfonyl)methane with a hydride of said alkali metal. A process according to claim 2, comprising a preliminary step of preparing naphthalen-l-sulfonyl chloride by chlorinating sodium 1-naphthalenesulfonate by reaction with thionyl chloride. Use of an alkali metal organic salt according to claim 1 for the preparation of an electrolyte. Liquid electrolyte comprising an organic salt of alkali metal according to claim 1 dissolved in an organic solvent. Solid electrolyte comprising an organic alkali metal salt according to claim 1 and a polymer. Solid electrolyte according to claim 6, wherein said polymer comprises a repeating motif of formula (II): [Chem. 2] « (II) ''o' '■a'' V'4 '■ L ' J in which m is equal to 0, 1 or 2.

8. Solid electrolyte according to claim 7, wherein the molar ratio "alkali metal organic salt / polymer carbonate groups" [M] / [CO3] is between 1 / 2 and 1 / 40.

9. Electrochemical cell for battery comprising a positive electrode, a negative electrode, an electrolyte and optionally a separator disposed between said positive electrode and said negative electrode, characterized in that said electrolyte is a liquid electrolyte according to claim 5 or a solid electrolyte according to any one of claims 6 to 8.

10. Battery comprising at least one electrochemical cell according to claim 9.

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